JPH03198905A - Control method for cooling rolled stock - Google Patents

Abstract

PURPOSE:To improve the control accuracy of coiling temp. over the full length of a rolled stock by detecting the temp. of the tip part of a rolled stock which is rolled while accelerating the speed and correcting the target temp. in the tip part where is cooled by comparing with the target temp. CONSTITUTION:In a sampling part 11, the moving speed V of the rolled stock is inputted and the actual value Tca of coiling temp. of the rolled stock is sampled at every fixed length based on this speed. The difference between the actual value Tca of coiling temp. and the target coiling temp. that is inputted in the sampling part 11 is determined as Tc(X) and given to a computing part 12. In the computing part 12, an acceleration length Xt is inputted and the mean value of the difference between the actual value of coiling temp. and the target coiling temp. is determined and given to a learning operating part 13. ln the learning operating part 13, a feedback value for the tip part of the material to be rolled which is next rolled is determined and stored in a learning table 14 and, in an objective temp. computing part 15, the objective value of coiling temp. is determined. And the determined objective value of coiling temp. is given to a cooling control operation part 16 and, in the operation part 16, water injecting quantity or the like is calculated by the objective value and a command for water injection is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cooling control method after finishing rolling of a rolled material such as a steel plate manufactured by hot rolling.

[Prior art]

FIG. 1 is a schematic diagram showing the configuration of an apparatus for cooling a rolled material to a predetermined temperature after hot finish rolling. After being sequentially hot-rolled in a plurality of rolling mills (not shown), the rolled material 1 sent out from the finishing mill 2 passes through a hot run table 3 and is wound up into a winding a4. The finish rolling mill 2 is provided with a speed detector 6 for detecting the rolling speed of the rolled material 1. Further, on the exit side of the finishing rolling mill 2, for example, an X-ray thickness gauge 7 and a finishing exit thermometer 8 are provided, and the thickness of the rolled material 1 and the temperature on the finishing exit side are detected by these.

Speed detector6. Detection signals from the thickness gauge 7 and the finishing exit thermometer 8 are given to the cooling control device 5.

The hot run table 3 is provided with a plurality of conveyance rollers (not shown), and a cooling bank 3a and a fine adjustment cooling bank 3b are provided between these in order from the finish rolling mill 2 side. The cooling bank 3a and the fine-adjustment cooling bank 3b are configured by disposing a plurality of water injection banks over the conveyance path of the rolled material 1, and each water injection bank is provided with water for the rolled material 1 delivered from the finishing rolling mill 2. It is equipped with cooling sprays that inject water from above and below, and the water injection operation is controlled for each water injection bank, and the spray pattern of the water injection bank to be used is determined. The spray pattern and the water injection amount are controlled based on a water injection command output from the cooling control device 5, respectively.

A winding thermometer 9 is provided on the exit side of the hot run table 3, and detects the temperature of the rolled material 1 that is wound up by the winder 4 after being cooled by the fine adjustment cooling bank 3b. . The winding machine 4 is provided with a winding speed detector 10 for detecting the winding speed. Detection signals from the winding thermometer 9 and the winding speed detector 10 are provided to the cooling control device 5.

The cooling control device 5 performs cooling control by the cooling bank 3a and the fine adjustment cooling bank 3b for cooling the temperature of the rolled material 1 after hot rolling to a predetermined temperature over the entire length from the leading edge to the trailing edge as follows. Do it like this.

First, the temperature and thickness of the rolled material 1 after finish rolling are input from the thickness gauge 7 and finish exit thermometer 8, respectively, and these input values and the moving speed of the rolled material 1 are calculated from the rolling speed detected by the speed detector 6. Based on the detected value, the amount of water required to achieve a predetermined winding temperature is calculated, a spray pattern for the cooling bank 3a is determined, and a water injection command is output to the cooling bank 3a. The moving speed of the rolled material 1 is detected by the winding speed detector 10 after the rear end of the rolled material 1 is sent out from the finishing mill 2. This calculation is performed for a certain period of time or every certain length of the rolled material l.

By the way, such cooling control is feedforward control based on prediction, and it is very difficult to achieve a predetermined coiling temperature over the entire length of the rolled material 1. Therefore,
The actual value of the winding temperature measured by the winding thermometer 9 is compared with a predetermined winding temperature, and a so-called in-bar feedback control is performed to issue a water injection command to the fine adjustment cooling bank 3b to correct the difference. It is being said.

[Problem to be solved by the invention]

However, even with a cooling control method that uses both feedforward control and feedbank control as described above, there is a problem in that the temperature at the tip of the rolled material is more likely to deviate from the target coiling temperature than at the middle part. be. The main reason for this is that the speed of the tip portion of the rolled material is being accelerated when it is rolled by each rolling mill. In other words, each rolling mill sets the rolling speed according to the required thickness, material quality, etc., but in order to carry out rolling at this speed, the tip of the rolled material that is transported starts rolling at a slightly lower speed. The rolling speed is controlled so that the rolling speed is gradually increased to perform rolling at a predetermined speed.

For this reason, the tip of the rolled material where the rolling speed has accelerated is
The temperature after finish rolling of this material is in an unsteady state, resulting in a delay in response to a water injection command, a sudden change in heat transfer due to contact with the conveyance roller of the hot run table, or a deviation from the required thickness. It is easier to be affected by various disturbances than the middle part and beyond.

Therefore, in response to the above-mentioned disturbances, adjustments have been made such as making corrections based on the heat transfer coefficient and setting in advance so that the amount of water injected is small only at the tip, but in both cases - Since the correction is fixed and fixed, it has been impossible to stably control the cooling of the tip over a long period of time for a rolled material whose rolling tendency changes from moment to moment.

The present invention has been made in view of the above circumstances, and provides a cooling control method for a rolled material that makes it possible to perform stable cooling control over a long period of time for the tip end of the rolled material that is subject to various disturbances. With the goal.

[Means to solve the problem]

In the cooling control method for rolled materials according to the present invention, the tip portions of the rolled materials are rolled in a hot rolling mill while being accelerated to a predetermined rolling speed, and after the tip portion and the subsequent portions are rolled at the predetermined rolling speed, a cooling device is installed. In a cooling control method for a rolled material, the cooling control method of the cooling device is performed so that the temperature in the winder matches a target temperature for a plurality of rolled materials that are cooled in a winder and sequentially wound on a winder. , the temperature of the tip of the rolled material rolled while being accelerated in the winding machine is detected, and based on the result of comparing this detected value with the target temperature, the material is then cooled in a cooling device. It is characterized by modifying the target temperature at the tip of the rolled material.

[Effect]

After being sequentially rolled and cooled in a cooling device, the rolled material is accelerated and the temperature of the tip of the rolled material in the winder is detected, and this temperature is compared with a target temperature. Based on the comparison result, the target temperature at the tip of the rolled material that is subsequently rolled and cooled is corrected.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on drawings showing embodiments thereof. The apparatus configuration shown in FIG. 1 can be used to carry out the cooling control method for rolled material according to the present invention, and its explanation will be omitted here.

FIG. 2 is a block diagram showing the control state of the method of the present invention in the cooling control device 5. First, the sampling section 11
inputs the moving speed (■) of the rolled material, and samples the actual winding temperature value Tea of the rolled material for each fixed length based on this speed.

FIG. 3 is a graph showing the relationship between the moving speed (1) of the rolled material and the time T, where the vertical axis shows the moving speed and the horizontal axis shows the time. The acceleration length of the rolling speed is set in advance from the start of rolling to the sand diameter t, that is, from the tip 0 of the rolled material to Xt, and accordingly, the moving speed ■ is accelerated from the speed vI to the speed ■2.

Fig. 4 is a graph showing the relationship between the actual value Tea of the coiling temperature and the length X of the rolled material, where the vertical axis shows the actual value of the coiling temperature and the horizontal axis shows the length of the rolled material. .

The difference between the actual value Tea of the winding temperature and the target winding temperature Tcr (broken line) which is input to the sampling section 11 is indicated by hatching.

This difference is determined as ΔTc(x) using the following equation (1) and is provided to the Δ〒7 calculating section 12.

ΔTc (x) = Tca (x) − Tcr
-(1) The ΔTc calculation unit 12 inputs the acceleration length
The average value Δ■ of Tc(Xl) is determined using the following equation (2).

This average value ΔT□ is given to the learning calculation unit 13, and the learning calculation unit 13 calculates the feedback value ΔT□ for the tip portion of the rolled material to be rolled next using the following equation (3).

ΔT″c1.=ΔT″C+i−1+α・ΔTc−
(31 Here, ΔT''C+i-1 is the feedback value for the tip of the previous, i.e., i-1th rolled material, and is read from the learning table 14. Also, α is the gain.

The obtained ΔT ”C+ + is obtained from the learning table 14.
and is fed back to the target value for the winding temperature of the tip end of the next rolled material. That is, the target temperature calculation section 15
is the length X using the learning feedbank value ΔT”.1.
The target value Tc of the coiling temperature of the rolled material in .

aim (X) is determined using the following formula (4).

□(4) However, Tcr is the target winding temperature and the obtained winding temperature aim value Tc, aio+ (x) is given to the cooling control calculation unit 16, and the cooling control calculation unit 16 is set to the target value Tc, aim f)1. Based on this, the water injection amount, spray pattern, etc. are calculated and a water injection command is output.

In addition, the amount of correction of the target coiling temperature value for the tip portion of the rolled material rolled this time is the previous feedback value ΔT ”
It is determined in (4) above using C+ + -1.

FIG. 5 is an example of a graph showing the relationship between the target winding temperature value Tc, aim and the length X of the rolled material. The target value of the tip portion 0-xL of the rolled material is set such that it gradually increases from a target value lower than the target winding temperature Tcr and reaches the target winding temperature Tcr at Xt. The target winding temperature Tcr remains the target value for the intermediate and rear end portions after Xt.

The results of producing hot rolled steel sheets using the cooling control method as described above will be described below. The thickness of the steel plate is 2.0~3.2s*
, width 900-1250m, target winding temperature 560-6
The temperature was set at 40°C, and 120 pieces were manufactured. As a result, we investigated the number of steel plates that fell within a range of ±25°C of the target coiling temperature for 95% of the middle part of a single steel plate, excluding the leading and trailing ends. , the method of the present invention improved to 89%.

〔effect〕

As described above, in the cooling control method for a rolled material according to the present invention, the target temperature is corrected based on the actual value of the previous coiling temperature of the rolled material also for the tip portion of the rolled material that is rolled while being accelerated. Since feedback is provided, it is possible to significantly prevent the tip end from deviating from the target temperature compared to conventional methods, and the control accuracy of the coiling temperature can be improved over the entire length of the rolled material over a long period of time. has excellent effects.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing the configuration of an apparatus for carrying out the cooling control method for rolled material according to the present invention, Fig. 2 is a block diagram showing the control state, and Fig. 3 shows the moving speed and time of the rolled material. Figure 4 is a graph showing the relationship between the actual value of the coiling temperature and the length of the rolled material. Figure 5 is a graph showing the relationship between the target value of the coiling temperature and the length of the rolled material. It is a graph. ■...Rolled material 2...Final rolling a 3a...
Cooling bank 4... Winder 5... Cooling control device
9... Winding thermometer

Claims (1)

[Claims] 1. The tip portions are rolled in a hot rolling mill while being accelerated to a predetermined rolling speed, and after the tip portions are rolled at a predetermined rolling speed, they are cooled in a cooling device. A cooling control method for a rolled material in which cooling control is performed on the cooling device so that a temperature in the winder matches a target temperature for a plurality of rolled materials that are sequentially wound up on a winder. The temperature of the tip of the rolled material in the winding machine is detected, and based on the result of comparing this detected value with the target temperature, the tip of the rolled material is cooled next in a cooling device. A cooling control method for a rolled material, the method comprising modifying a target temperature in a portion.